-
Document Number: 318734-017
Intel® Core™2 Duo Processor E8000∆ and E7000∆ Series, Intel®
Pentium® Dual-Core Processor E6000∆ and E5000∆ Series, and Intel®
Celeron® Processor E3000∆ Series Thermal and Mechanical Design
Guidelines November 2010
-
2 Thermal and Mechanical Design Guidelines
THIS DOCUMENT AND RELATED MATERIALS AND INFORMATION ARE PROVIDED
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http://www.intel.com .
The Intel® Core™2 Duo processor E8000, E7000 series and Intel®
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Celeron® processor E3000 series components may contain design
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*Other names and brands may be claimed as the property of
others.
Copyright © 2008–2010 Intel Corporation
http://www.intel.com/�
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Thermal and Mechanical Design Guidelines 3
Contents 1 Introduction
......................................................................................................
9
1.1 Document Goals and Scope
......................................................................
9 1.1.1 Importance of Thermal Management
............................................ 9 1.1.2 Document Goals
........................................................................
9 1.1.3 Document Scope
......................................................................
10
1.2 References
............................................................................................
11 1.3 Definition of
Terms.................................................................................
11
2 Processor Thermal/Mechanical Information
.......................................................... 13 2.1
Mechanical Requirements
........................................................................
13
2.1.1 Processor Package
....................................................................
13 2.1.2 Heatsink Attach
........................................................................
15
2.1.2.1 General Guidelines
..................................................... 15 2.1.2.2
Heatsink Clip Load Requirement ..................................
15 2.1.2.3 Additional Guidelines
.................................................. 16
2.2 Thermal Requirements
...........................................................................
16 2.2.1 Processor Case Temperature
...................................................... 16 2.2.2
Thermal Profile
.........................................................................
17 2.2.3 Thermal Solution Design Requirements
....................................... 17 2.2.4 TCONTROL
...................................................................................
18
2.3 Heatsink Design Considerations
............................................................... 19
2.3.1 Heatsink Size
...........................................................................
20 2.3.2 Heatsink Mass
..........................................................................
20 2.3.3 Package IHS Flatness
................................................................ 21
2.3.4 Thermal Interface Material
......................................................... 21
2.4 System Thermal Solution Considerations
.................................................. 22 2.4.1 Chassis
Thermal Design Capabilities
............................................ 22 2.4.2 Improving
Chassis Thermal Performance .....................................
22 2.4.3 Summary
................................................................................
23
2.5 System Integration Considerations
........................................................... 23
3 Thermal Metrology
............................................................................................
25 3.1 Characterizing Cooling Performance Requirements
..................................... 25
3.1.1 Example
..................................................................................
26 3.2 Processor Thermal Solution Performance Assessment
................................. 27 3.3 Local Ambient Temperature
Measurement Guidelines ................................. 27 3.4
Processor Case Temperature Measurement Guidelines
................................ 30
4 Thermal Management Logic and Thermal Monitor Feature
...................................... 31 4.1 Processor Power
Dissipation
....................................................................
31 4.2 Thermal Monitor Implementation
.............................................................
31
4.2.1 PROCHOT# Signal
....................................................................
32 4.2.2 Thermal Control Circuit
.............................................................
32
4.2.2.1 Thermal Monitor
........................................................ 32 4.2.3
Thermal Monitor 2
....................................................................
33 4.2.4 Operation and Configuration
...................................................... 34 4.2.5
On-Demand Mode
.....................................................................
35
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4 Thermal and Mechanical Design Guidelines
4.2.6 System Considerations
.............................................................. 35
4.2.7 Operating System and Application Software Considerations
........... 36 4.2.8 THERMTRIP# Signal
..................................................................
36 4.2.9 Cooling System Failure Warning
................................................. 36 4.2.10 Digital
Thermal Sensor
.............................................................. 37
4.2.11 Platform Environmental Control Interface (PECI)
.......................... 38
5 Balanced Technology Extended (BTX) Thermal/Mechanical Design
Information ......... 39 5.1 Overview of the BTX Reference Design
..................................................... 39
5.1.1 Target Heatsink Performance
..................................................... 39 5.1.2
Acoustics
.................................................................................
40 5.1.3 Effective Fan Curve
...................................................................
41 5.1.4 Voltage Regulator Thermal Management
...................................... 42 5.1.5 Altitude
...................................................................................
43 5.1.6 Reference Heatsink Thermal Validation
........................................ 43
5.2 Environmental Reliability Testing
............................................................. 43
5.2.1 Structural Reliability Testing
...................................................... 43
5.2.1.1 Random Vibration Test Procedure
................................ 43 5.2.1.2 Shock Test Procedure
................................................. 44
5.2.2 Power Cycling
..........................................................................
45 5.2.3 Recommended BIOS/CPU/Memory Test Procedures
...................... 46
5.3 Material and Recycling
Requirements........................................................
46 5.4 Safety Requirements
..............................................................................
47 5.5 Geometric Envelope for Intel® Reference BTX Thermal Module
Assembly ...... 47 5.6 Preload and TMA Stiffness
.......................................................................
48
5.6.1 Structural Design Strategy
......................................................... 48 5.6.2
TMA Preload verse Stiffness
....................................................... 48
6 ATX Thermal/Mechanical Design Information
........................................................ 51 6.1 ATX
Reference Design Requirements
........................................................ 51 6.2
Validation Results for Reference Design
.................................................... 53
6.2.1 Heatsink Performance
............................................................... 53
6.2.2 Acoustics
.................................................................................
54 6.2.3 Altitude
...................................................................................
54 6.2.4 Heatsink Thermal Validation
....................................................... 55
6.3 Environmental Reliability Testing
............................................................. 55
6.3.1 Structural Reliability Testing
...................................................... 55
6.3.1.1 Random Vibration Test Procedure
................................ 55 6.3.1.2 Shock Test Procedure
................................................. 56
6.3.2 Power Cycling
..........................................................................
57 6.3.3 Recommended BIOS/CPU/Memory Test Procedures
...................... 58
6.4 Material and Recycling
Requirements........................................................
58 6.5 Safety Requirements
..............................................................................
59 6.6 Geometric Envelope for Intel® Reference ATX Thermal
Mechanical Design ..... 59 6.7 Reference Attach Mechanism
...................................................................
60
6.7.1 Structural Design Strategy
......................................................... 60 6.7.2
Mechanical Interface to the Reference Attach Mechanism
.............. 61
7 Intel® Quiet System Technology (Intel® QST)
...................................................... 63 7.1
Intel® QST Algorithm
..............................................................................
63
7.1.1 Output Weighting Matrix
............................................................ 64
7.1.2 Proportional-Integral-Derivative (PID)
......................................... 64
7.2 Board and System Implementation of Intel® QST
....................................... 66
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Thermal and Mechanical Design Guidelines 5
7.3 Intel® QST Configuration and Tuning
........................................................ 68 7.4 Fan
Hub Thermistor and Intel® QST
......................................................... 68
Appendix A LGA775 Socket Heatsink Loading
........................................................................
69 A.1 LGA775 Socket Heatsink Considerations
................................................... 69 A.2 Metric
for Heatsink Preload for ATX/uATX Designs Non-Compliant with
Intel®
Reference Design
...................................................................................
69 A.3 Heatsink Preload Requirement Limitations
................................................. 69
A.3.1 Motherboard Deflection Metric
Definition...................................... 70 A.3.2 Board
Deflection Limits
.............................................................. 71
A.3.3 Board Deflection Metric Implementation Example
......................... 72 A.3.4 Additional
Considerations...........................................................
73
A.3.4.1 Motherboard Stiffening Considerations
......................... 74 A.4 Heatsink Selection Guidelines
..................................................................
74
Appendix B Heatsink Clip Load Metrology
.............................................................................
75 B.1 Overview
..............................................................................................
75 B.2 Test Preparation
....................................................................................
75
B.2.1 Heatsink Preparation
.................................................................
75 B.2.2 Typical Test Equipment
.............................................................
78
B.3 Test Procedure Examples
........................................................................
78 B.3.1 Time-Zero, Room Temperature Preload Measurement
................... 79 B.3.2 Preload Degradation under Bake
Conditions ................................. 79
Appendix C Thermal Interface Management
..........................................................................
81 C.1 Bond Line Management
..........................................................................
81 C.2 Interface Material Area
...........................................................................
81 C.3 Interface Material Performance
................................................................
81
Appendix D Case Temperature Reference Metrology
............................................................... 83
D.1 Objective and
Scope...............................................................................
83 D.2 Supporting Test Equipment
.....................................................................
83 D.3 Thermal Calibration and Controls
............................................................. 85
D.4 IHS Groove
...........................................................................................
85 D.5 Thermocouple Attach Procedure
...............................................................
89
D.5.1 Thermocouple Conditioning and Preparation
................................. 89 D.5.2 Thermocouple Attachment
to the IHS .......................................... 90 D.5.3
Solder Process
.........................................................................
95 D.5.4 Cleaning and Completion of Thermocouple Installation
.................. 98
D.6 Thermocouple Wire Management
........................................................... 102
Appendix E Balanced Technology Extended (BTX) System Thermal
Considerations .................. 103
Appendix F Fan Performance for Reference Design
..............................................................
107
Appendix G Mechanical Drawings
.......................................................................................
109
Appendix H Intel® Enabled Reference Solution Information
................................................... 125
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6 Thermal and Mechanical Design Guidelines
Figures
Figure 2-1. Package IHS Load Areas
...................................................................
13 Figure 2-2. Processor Case Temperature Measurement Location
............................. 17 Figure 2-3. Example Thermal
Profile....................................................................
18 Figure 3-1. Processor Thermal Characterization Parameter
Relationships ................. 26 Figure 3-2. Locations for
Measuring Local Ambient Temperature, Active ATX Heatsink29 Figure
3-3. Locations for Measuring Local Ambient Temperature, Passive
Heatsink ... 29 Figure 4-1. Thermal Monitor
Control....................................................................
33 Figure 4-2. Thermal Monitor 2 Frequency and Voltage Ordering
.............................. 34 Figure 4-3. TCONTROL for Digital
Thermal Sensor
..................................................... 37 Figure
5-1. Effective TMA Fan Curves with Reference Extrusion
.............................. 42 Figure 5-2. Random Vibration PSD
......................................................................
44 Figure 5-3. Shock Acceleration Curve
..................................................................
44 Figure 5-4. Intel® Type II TMA 65W Reference Design
........................................... 47 Figure 5-5. Upward
Board Deflection During Shock
............................................... 48 Figure 5-6.
Minimum Required Processor Preload to Thermal Module Assembly
Stiffness
....................................................................................................
49 Figure 5-7. Thermal Module Attach Pointes and Duct-to-SRM
Interface Features ....... 50 Figure 6-1. E18764-001 Reference
Design – Exploded View ................................... 52
Figure 6-2. Bottom View of Copper Core Applied by TC-1996 Grease
....................... 52 Figure 6-3. Random Vibration PSD
......................................................................
56 Figure 6-4. Shock Acceleration Curve
..................................................................
56 Figure 6-5. Upward Board Deflection during Shock
................................................ 60 Figure 6-6.
Reference Clip/Heatsink Assembly
...................................................... 61 Figure
6-7. Critical Parameters for Interfacing to Reference Clip
............................. 62 Figure 6-8. Critical Core
Dimension
.....................................................................
62 Figure 7-1. Intel® QST Overview
........................................................................
64 Figure 7-2. PID Controller Fundamentals
............................................................. 65
Figure 7-3. Intel® QST Platform Requirements
..................................................... 66 Figure
7-4. Example Acoustic Fan Speed Control Implementation
........................... 67 Figure 7-5. Digital Thermal Sensor
and Thermistor ............................................... 68
Figure 7-6. Board Deflection Definition
................................................................ 71
Figure 7-7. Example—Defining Heatsink Preload Meeting Board
Deflection Limit ....... 73 Figure 7-8. Load Cell Installation in
Machined Heatsink Base Pocket – Bottom View .. 76 Figure 7-9. Load
Cell Installation in Machined Heatsink Base Pocket – Side View
...... 77 Figure 7-10. Preload Test Configuration
............................................................... 77
Figure 7-11. Omega Thermocouple
.....................................................................
84 Figure 7-12. 775-LAND LGA Package Reference Groove Drawing at 6
o’clock Exit ..... 86 Figure 7-13. 775-LAND LGA Package Reference
Groove Drawing at 3 o’clock Exit (Old
Drawing)
...................................................................................................
87 Figure 7-14. IHS Groove at 6 o’clock Exit on the 775-LAND LGA
Package ................ 88 Figure 7-15. IHS Groove at 6 o’clock
Exit Orientation Relative to the LGA775 Socket 88 Figure 7-16.
Inspection of Insulation on Thermocouple
.......................................... 89 Figure 7-17. Bending
the Tip of the Thermocouple
................................................ 90 Figure 7-18.
Securing Thermocouple Wires with Kapton* Tape Prior to Attach
.......... 90 Figure 7-19. Thermocouple Bead Placement
......................................................... 91 Figure
7-20. Position Bead on the Groove Step
..................................................... 92 Figure
7-21. Detailed Thermocouple Bead Placement
............................................ 92 Figure 7-22. Third
Tape Installation
....................................................................
93 Figure 7-23. Measuring Resistance between Thermocouple and IHS
........................ 93 Figure 7-24. Applying Flux to the
Thermocouple Bead ........................................... 94
Figure 7-25. Cutting Solder
................................................................................
94 Figure 7-26. Positioning Solder on IHS
................................................................
95
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Thermal and Mechanical Design Guidelines 7
Figure 7-27. Solder Station Setup
.......................................................................
96 Figure 7-28. View Through Lens at Solder Station
................................................. 97 Figure 7-29.
Moving Solder back onto Thermocouple Bead
..................................... 97 Figure 7-30. Removing
Excess Solder
..................................................................
98 Figure 7-31. Thermocouple placed into groove
..................................................... 99 Figure
7-32. Removing Excess Solder
..................................................................
99 Figure 7-33. Filling Groove with Adhesive
.......................................................... 100
Figure 7-34. Application of Accelerant
............................................................... 100
Figure 7-35. Removing Excess Adhesive from IHS
.............................................. 101 Figure 7-36.
Finished Thermocouple Installation
................................................. 101 Figure 7-37.
Thermocouple Wire Management
.................................................... 102 Figure
7-38. System Airflow Illustration with System Monitor Point Area
Identified . 104 Figure 7-39. Thermal sensor Location Illustration
............................................... 105 Figure 7-40.
ATX/µATX Motherboard Keep-out Footprint Definition and Height
Restrictions for Enabling Components - Sheet 1
........................................... 110 Figure 7-41.
ATX/µATX Motherboard Keep-out Footprint Definition and Height
Restrictions for Enabling Components - Sheet 2
........................................... 111 Figure 7-42.
ATX/µATX Motherboard Keep-out Footprint Definition and Height
Restrictions for Enabling Components - Sheet 3
........................................... 112 Figure 7-43. BTX
Thermal Module Keep Out Volumetric – Sheet 1
......................... 113 Figure 7-44. BTX Thermal Module Keep
Out Volumetric – Sheet 2 ......................... 114 Figure 7-45.
BTX Thermal Module Keep Out Volumetric – Sheet 3
......................... 115 Figure 7-46. BTX Thermal Module Keep
Out Volumetric – Sheet 4 ......................... 116 Figure 7-47.
BTX Thermal Module Keep Out Volumetric – Sheet 5
......................... 117 Figure 7-48. ATX Reference Clip –
Sheet 1 .........................................................
118 Figure 7-49. ATX Reference Clip - Sheet 2
......................................................... 119
Figure 7-50. Reference Fastener - Sheet 1
......................................................... 120
Figure 7-51. Reference Fastener - Sheet 2
......................................................... 121
Figure 7-52. Reference Fastener - Sheet 3
......................................................... 122
Figure 7-53. Reference Fastener - Sheet 4
......................................................... 123
Figure 7-54. Intel® E18764-001 Reference Solution Assembly
.............................. 124
Tables
Table 2–1. Heatsink Inlet Temperature of Intel® Reference
Thermal Solutions .......... 22 Table 2–2. Heatsink Inlet
Temperature of Intel® Boxed Processor Thermal Solutions . 22 Table
5–1. Balanced Technology Extended (BTX) Type II Reference TMA
Performance39 Table 5–2. Acoustic Targets
...............................................................................
40 Table 5–3. VR Airflow Requirements
....................................................................
42 Table 5–4. Processor Preload Limits
....................................................................
49 Table 6–1. E18764-001 Reference Heatsink Performance
...................................... 53 Table 6–2. Acoustic
Results for ATX Reference Heatsink (E18764-001)
.................... 54 Table 7–1. Board Deflection Configuration
Definitions ............................................ 70 Table
7–2. Typical Test Equipment
......................................................................
78 Table 7–3. Fan Electrical Performance Requirements
........................................... 107 Table 7–4. Intel®
Representative Contact for Licensing Information of BTX
Reference
Design
....................................................................................................
125 Table 7–5. E18764-001 Reference Thermal Solution Providers
............................. 125 Table 7–6. BTX Reference Thermal
Solution Providers .........................................
126
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8 Thermal and Mechanical Design Guidelines
Revision History
Revision Number
Description Revision
001 • Initial release. January 2008
002 • Added Intel® Core™2 Duo processor E8300 and E7200 April
2008
003 • Added Intel® Core™2 Duo processor E8600 and E7300 August
2008
004 • Added Intel® Pentium dual-core processor E5200 August
2008
005 • Added Intel® Core™2 Duo processor E7400 October 2008
006 • Added Intel® Pentium dual-core processor E5300 December
2008
007 • Added Intel® Pentium dual-core processor E5400 • Added
Intel® Core™2 Duo processor E7500
January 2009
008 • Added Intel® Pentium dual-core processor E6300 May
2009
009 • Added Intel® Core™2 Duo processor E7600 June 2009
010 • Added Intel® Pentium dual-core processor E6500 August
2009
011 • Intel® Celeron® processor E3x00 series August 2009
012 • Added Intel® Pentium dual-core processor E6600 • Intel®
Celeron® processor E3400
January 2010
013 • Added Intel® Pentium dual-core processor E5500 April
2010
014 • Added Intel® Pentium dual-core processor E6700 June
2010
015 • Added Intel® Pentium dual-core processor E5700 August
2010
016
• Added Intel® Pentium dual-core processor E6800 • Added Intel®
Celeron® processor E3500 • Changed the processor numbering from
Intel Celeron processor E3x00
series to Intel Celeron processor E3000 series.
August 2010
017 • Added Intel® Pentium dual-core processor E5800 November
2010
§
-
Introduction
Thermal and Mechanical Design Guidelines 9
1 Introduction
1.1 Document Goals and Scope
1.1.1 Importance of Thermal Management
The objective of thermal management is to ensure that the
temperatures of all components in a system are maintained within
their functional temperature range. Within this temperature range,
a component is expected to meet its specified performance.
Operation outside the functional temperature range can degrade
system performance, cause logic errors or cause component and/or
system damage. Temperatures exceeding the maximum operating limit
of a component may result in irreversible changes in the operating
characteristics of this component.
In a system environment, the processor temperature is a function
of both system and component thermal characteristics. The system
level thermal constraints consist of the local ambient air
temperature and airflow over the processor as well as the physical
constraints at and above the processor. The processor temperature
depends in particular on the component power dissipation, the
processor package thermal characteristics, and the processor
thermal solution.
All of these parameters are affected by the continued push of
technology to increase processor performance levels and packaging
density (more transistors). As operating frequencies increase and
packaging size decreases, the power density increases while the
thermal solution space and airflow typically become more
constrained or remains the same within the system. The result is an
increased importance on system design to ensure that thermal design
requirements are met for each component, including the processor,
in the system.
1.1.2 Document Goals
Depending on the type of system and the chassis characteristics,
new system and component designs may be required to provide
adequate cooling for the processor. The goal of this document is to
provide an understanding of these thermal characteristics and
discuss guidelines for meeting the thermal requirements imposed on
single processor systems using the Intel® Core™2 Duo processor
E8000, E7000 series, Intel® Pentium® dual-core processor E6000,
E5000 series, and Intel® Celeron® processor E3000 series.
The concepts given in this document are applicable to any system
form factor. Specific examples used will be the Intel enabled
reference solution for ATX/uATX systems. See the applicable BTX
form factor reference documents to design a thermal solution for
that form factor.
-
Introduction
10 Thermal and Mechanical Design Guidelines
1.1.3 Document Scope This design guide supports the following
processors:
• Intel® Core™2 Duo processor E8000 series with 6 MB cache
applies to Intel® Core™2 Duo processors E8600, E8500, E8400, E8300,
E8200, and E8190
• Intel® Core™2 Duo processor E7000 series with 3 MB cache
applies to Intel® Core™2 Duo processors E7600, E7500, E7400, E7300,
and E7200
• Intel® Pentium® dual-core processor E5000 series with 2 MB
cache applies to Intel® Pentium® dual-core processors E5800, E5700,
E5500, E5400, E5300, and E5200
• Intel® Pentium® dual-core processor E6000 series with 2 MB
cache applies to Intel® Pentium® dual-core processor E6800, E6700,
E6600, E6500, and E6300
• Intel® Celeron® processor E3000 series with 1 MB cache applies
to the Intel® Celeron® processor E3500, E3400, E3300, and E3200
In this document when a reference is made to “the processor” it
is intended that this includes all the processors supported by this
document. If needed for clarity, the specific processor will be
listed.
In this document, when a reference is made to the “the reference
design” it is intended that this means ATX reference designs
(E18764-001) supported by this document. If needed for clarify, the
specific reference design will be listed.
In this document, when a reference is made to “the datasheet”,
the reader should refer to the Intel® Core™2 Duo Processor E8000
and E7000 Series Datasheet, Intel® Pentium® Dual-Core Processor
E6000 and E5000 Series Datasheet, and Intel® Celeron® Processor
E3000 Series Datasheet. If needed for clarity the specific
processor datasheet will be referenced.
Chapter 2 of this document discusses package thermal mechanical
requirements to design a thermal solution for the processor in the
context of personal computer applications. Chapter 3 discusses the
thermal solution considerations and metrology recommendations to
validate a processor thermal solution. Chapter 4 addresses the
benefits of the processor’s integrated thermal management logic for
thermal design. Chapter 5 gives information on the Intel reference
thermal solution for the processor in BTX platform. Chapter 6 gives
information on the Intel reference thermal solution for the
processor in ATX platform. Chapter 7 discusses the implementation
of acoustic fan speed control.
The physical dimensions and thermal specifications of the
processor that are used in this document are for illustration only.
Refer to the datasheet for the product dimensions, thermal power
dissipation and maximum case temperature. In case of conflict, the
data in the datasheet supersedes any data in this document.
-
Introduction
Thermal and Mechanical Design Guidelines 11
1.2 References Material and concepts available in the following
documents may be beneficial when reading this document.
Material and concepts available in the following documents may
be beneficial when reading this document.
Document Location
Intel® Core™2 Duo Processor E8000 and E7000 Series Datasheet
www.intel.com/design/processor/datashts/318732.htm
Intel® Pentium® Dual-Core Processor E6000 and E5000 Series
Datasheet
http://download.intel.com/design/processor/datashts/320467.pdf
Intel® Celeron® Processor E3000 Series Datasheet
http://download.intel.com/design/processor/datashts/322567.pdf
LGA775 Socket Mechanical Design Guide
http://developer.intel.com/design/Pentium4/guides/302666.htm
uATX SFF Design Guidance http://www.formfactors.org/
Fan Specification for 4-wire PWM Controlled Fans
http://www.formfactors.org/
ATX Thermal Design Suggestions http://www.formfactors.org/
microATX Thermal Design Suggestions
http://www.formfactors.org/
Balanced Technology Extended (BTX) System Design Guide
http://www.formfactors.org/
Thermally Advantaged Chassis Design Guide
http://www.intel.com/go/chassis/
1.3 Definition of Terms Term Description
TA The measured ambient temperature locally surrounding the
processor. The ambient temperature should be measured just upstream
of a passive heatsink or at the fan inlet for an active
heatsink.
TC The case temperature of the processor, measured at the
geometric center of the topside of the IHS.
TE The ambient air temperature external to a system chassis.
This temperature is usually measured at the chassis air inlets.
TS Heatsink temperature measured on the underside of the
heatsink base, at a location corresponding to TC.
TC-MAX The maximum case temperature as specified in a component
specification.
ΨCA
Case-to-ambient thermal characterization parameter (psi). A
measure of thermal solution performance using total package power.
This is defined as: (TC – TA) / Total Package Power. Note: Heat
source must be specified for Ψ measurements.
http://download.intel.com/design/processor/datashts/320467.pdf�http://download.intel.com/design/processor/datashts/320467.pdf�http://download.intel.com/design/processor/datashts/322567.pdf�http://download.intel.com/design/processor/datashts/322567.pdf�http://developer.intel.com/design/Pentium4/guides/302666.htm�http://developer.intel.com/design/Pentium4/guides/302666.htm�
-
Introduction
12 Thermal and Mechanical Design Guidelines
Term Description
ΨCS
Case-to-sink thermal characterization parameter. A measure of
thermal interface material performance using total package power.
This is defined as: (TC – TS) / Total Package Power.
Note: Heat source must be specified for Ψ measurements.
ΨSa
Sink-to-ambient thermal characterization parameter. A measure of
heatsink thermal performance using total package power. This is
defined as: (TS – TA) / Total Package Power.
Note: Heat source must be specified for Ψ measurements.
TIM Thermal Interface Material: The thermally conductive
compound between the heatsink and the processor case. This material
fills the air gaps and voids, and enhances the transfer of the heat
from the processor case to the heatsink.
PMAX The maximum power dissipated by a semiconductor
component.
TDP Thermal Design Power: a power dissipation target based on
worst-case applications. Thermal solutions should be designed to
dissipate the thermal design power.
IHS Integrated Heat Spreader: a thermally conductive lid
integrated into a processor package to improve heat transfer to a
thermal solution through heat spreading.
LGA775 Socket
The surface mount socket designed to accept the processors in
the 775–Land LGA package.
ACPI Advanced Configuration and Power Interface.
Bypass Bypass is the area between a passive heatsink and any
object that can act to form a duct. For this example, it can be
expressed as a dimension away from the outside dimension of the
fins to the nearest surface.
Thermal Monitor
A feature on the processor that attempts to keep the processor
die temperature within factory specifications.
TCC Thermal Control Circuit: Thermal Monitor uses the TCC to
reduce die temperature by lowering the effective processor
frequency when the die temperature has exceeded its operating
limits.
DTS Digital Thermal Sensor: Processor die sensor temperature
defined as an offset from the onset of PROCHOT#.
FSC Fan Speed Control: Thermal solution that includes a variable
fan speed which is driven by a PWM signal and uses the on-die
thermal diode as a reference to change the duty cycle of the PWM
signal.
TCONTROL TCONTROL is the specification limit for use with the
on-die thermal diode.
PWM Pulse width modulation is a method of controlling a variable
speed fan. The enabled 4-wire fans use the PWM duty cycle % from
the fan speed controller to modulate the fan speed.
Health Monitor
Component
Any standalone or integrated component that is capable of
reading the processor temperature and providing the PWM signal to
the 4-pin fan header.
BTX Balanced Technology Extended.
TMA Thermal Module Assembly. The heatsink, fan and duct assembly
for the BTX thermal solution
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Processor Thermal/Mechanical Information
Thermal and Mechanical Design Guidelines 13
2 Processor Thermal/Mechanical Information
2.1 Mechanical Requirements
2.1.1 Processor Package The processors covered in the document
are packaged in a 775-Land LGA package that interfaces with the
motherboard using a LGA775 socket. Refer to the datasheet for
detailed mechanical specifications.
The processor connects to the motherboard through a land grid
array (LGA) surface mount socket. The socket contains 775 contacts
arrayed about a cavity in the center of the socket with solder
balls for surface mounting to the motherboard. The socket is named
LGA775 socket. A description of the socket can be found in the
LGA775 Socket Mechanical Design Guide.
The package includes an integrated heat spreader (IHS) that is
shown in Figure 2-1 for illustration only. Refer to the processor
datasheet for further information. In case of conflict, the package
dimensions in the processor datasheet supersedes dimensions
provided in this document.
Figure 2-1. Package IHS Load Areas
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Processor Thermal/Mechanical Information
14 Thermal and Mechanical Design Guidelines
The primary function of the IHS is to transfer the non-uniform
heat distribution from the die to the top of the IHS, out of which
the heat flux is more uniform and spread over a larger surface area
(not the entire IHS area). This allows more efficient heat transfer
out of the package to an attached cooling device. The top surface
of the IHS is designed to be the interface for contacting a
heatsink.
The IHS also features a step that interfaces with the LGA775
socket load plate, as described in LGA775 Socket Mechanical Design
Guide. The load from the load plate is distributed across two sides
of the package onto a step on each side of the IHS. It is then
distributed by the package across all of the contacts. When
correctly actuated, the top surface of the IHS is above the load
plate allowing proper installation of a heatsink on the top surface
of the IHS. After actuation of the socket load plate, the seating
plane of the package is flush with the seating plane of the socket.
Package movement during socket actuation is along the Z direction
(perpendicular to substrate) only. Refer to the LGA775 Socket
Mechanical Design Guide for further information about the LGA775
socket.
The processor package has mechanical load limits that are
specified in the processor datasheet. The specified maximum static
and dynamic load limits should not be exceeded during their
respective stress conditions. These include heatsink installation,
removal, mechanical stress testing, and standard shipping
conditions.
• When a compressive static load is necessary to ensure thermal
performance of the thermal interface material between the heatsink
base and the IHS, it should not exceed the corresponding
specification given in the processor datasheet.
• When a compressive static load is necessary to ensure
mechanical performance, it should remain in the minimum/maximum
range specified in the processor datasheet
• The heatsink mass can also generate additional dynamic
compressive load to the package during a mechanical shock event.
Amplification factors due to the impact force during shock must be
taken into account in dynamic load calculations. The total
combination of dynamic and static compressive load should not
exceed the processor datasheet compressive dynamic load
specification during a vertical shock. For example, with a 0.550 kg
[1.2 lb] heatsink, an acceleration of 50G during an 11 ms
trapezoidal shock with an amplification factor of 2 results in
approximately a 539 N [117 lbf] dynamic load on the processor
package. If a 178 N [40 lbf] static load is also applied on the
heatsink for thermal performance of the thermal interface material
the processor package could see up to a 717 N [156 lbf]. The
calculation for the thermal solution of interest should be compared
to the processor datasheet specification.
No portion of the substrate should be used as a load- bearing
surface.
Finally, the processor datasheet provides package handling
guidelines in terms of maximum recommended shear, tensile and
torque loads for the processor IHS relative to a fixed substrate.
These recommendations should be followed in particular for heatsink
removal operations.
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Processor Thermal/Mechanical Information
Thermal and Mechanical Design Guidelines 15
2.1.2 Heatsink Attach
2.1.2.1 General Guidelines
There are no features on the LGA775 socket to directly attach a
heatsink: a mechanism must be designed to attach the heatsink
directly to the motherboard. In addition to holding the heatsink in
place on top of the IHS, this mechanism plays a significant role in
the robustness of the system in which it is implemented, in
particular:
• Ensuring thermal performance of the thermal interface material
(TIM) applied between the IHS and the heatsink. TIMs based on phase
change materials are very sensitive to applied pressure: the higher
the pressure, the better the initial performance. TIMs such as
thermal greases are not as sensitive to applied pressure. Designs
should consider a possible decrease in applied pressure over time
due to potential structural relaxation in retention components.
• Ensuring system electrical, thermal, and structural integrity
under shock and vibration events. The mechanical requirements of
the heatsink attach mechanism depend on the mass of the heatsink
and the level of shock and vibration that the system must support.
The overall structural design of the motherboard and the system
have to be considered when designing the heatsink attach mechanism.
Their design should provide a means for protecting LGA775 socket
solder joints. One of the strategies for mechanical protection of
the socket is to use a preload and high stiffness clip. This
strategy is implemented by the reference design and described in
Section 6.7.
Note: Package pull-out during mechanical shock and vibration is
constrained by the LGA775 socket load plate (refer to the LGA775
Socket Mechanical Design Guide for further information).
2.1.2.2 Heatsink Clip Load Requirement
The attach mechanism for the heatsink developed to support the
processor should create a static preload on the package between 18
lbf and 70 lbf throughout the life of the product for designs
compliant with the reference design assumptions:
• 72 mm x 72 mm mounting hole span for ATX (refer to Figure
7-40)
• TMA preload versus stiffness for BTX within the limits shown
on Figure 5-6
• And no board stiffening device (backing plate, chassis attach,
and so forth).
The minimum load is required to protect against fatigue failure
of socket solder joint in temperature cycling.
It is important to take into account potential load degradation
from creep over time when designing the clip and fastener to the
required minimum load. This means that, depending on clip
stiffness, the initial preload at beginning of life of the product
may be significantly higher than the minimum preload that must be
met throughout the life of the product. For additional guidelines
on mechanical design, in particular on designs departing from the
reference design assumptions refer to Appendix A.
For clip load metrology guidelines, refer to Appendix B.
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Processor Thermal/Mechanical Information
16 Thermal and Mechanical Design Guidelines
2.1.2.3 Additional Guidelines
In addition to the general guidelines given above, the heatsink
attach mechanism for the processor should be designed to the
following guidelines:
• Holds the heatsink in place under mechanical shock and
vibration events and applies force to the heatsink base to maintain
desired pressure on the thermal interface material. Note that the
load applied by the heatsink attach mechanism must comply with the
package specifications described in the processor datasheet. One of
the key design parameters is the height of the top surface of the
processor IHS above the motherboard. The IHS height from the top of
board is expected to vary from 7.517 mm to 8.167 mm. This data is
provided for information only, and should be derived from:
The height of the socket seating plane above the motherboard
after reflow, given in the LGA775 Socket Mechanical Design Guide
with its tolerances.
The height of the package, from the package seating plane to the
top of the IHS, and accounting for its nominal variation and
tolerances that are given in the corresponding processor
datasheet.
• Engages easily, and if possible, without the use of special
tools. In general, the heatsink is assumed to be installed after
the motherboard has been installed into the chassis.
• Minimizes contact with the motherboard surface during
installation and actuation to avoid scratching the motherboard.
2.2 Thermal Requirements Refer to the datasheet for the
processor thermal specifications. The majority of processor power
is dissipated through the IHS. There are no additional components
(such as BSRAMs) that generate heat on this package. The amount of
power that can be dissipated as heat through the processor package
substrate and into the socket is usually minimal.
The thermal limits for the processor are the Thermal Profile and
TCONTROL. The Thermal Profile defines the maximum case temperature
as a function of power being dissipated. TCONTROL is a
specification used in conjunction with the temperature reported by
the digital thermal sensor and a fan speed control method.
Designing to these specifications allows optimization of thermal
designs for processor performance and acoustic noise reduction.
2.2.1 Processor Case Temperature
For the processor, the case temperature is defined as the
temperature measured at the geometric center of the package on the
surface of the IHS. For illustration, Figure 2-2 shows the
measurement location for a 37.5 mm x 37.5 mm [1.474 in x 1.474 in]
775-Land LGA processor package with a 28.7 mm x 28.7 mm [1.13 in x
1.13 in] IHS top surface. Techniques for measuring the case
temperature are detailed in Section 3.4.
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Processor Thermal/Mechanical Information
Thermal and Mechanical Design Guidelines 17
Figure 2-2. Processor Case Temperature Measurement Location
37.5 mm
Measure TC at this point (geometric center of the package)
37.5
mm
37.5 mm
Measure TC at this point (geometric center of the package)
37.5
mm
2.2.2 Thermal Profile
The Thermal Profile defines the maximum case temperature as a
function of processor power dissipation. Refer to the datasheet for
the further information.
2.2.3 Thermal Solution Design Requirements
While the thermal profile provides flexibility for ATX /BTX
thermal design based on its intended target thermal environment,
thermal solutions that are intended to function in a multitude of
systems and environments need to be designed for the worst-case
thermal environment. The majority of ATX /BTX platforms are
targeted to function in an environment that will have up to a 35 °C
ambient temperature external to the system.
For ATX platforms, an active air-cooled design, assumed be used
in ATX Chassis, with a fan installed at the top of the heatsink
equivalent to the reference design (see Chapter 6) should be
designed to manage the processor TDP at an inlet temperature of 35
°C + 5°C = 40 °C.
For BTX platforms, a front-to-back cooling design equivalent to
Intel BTX TMA Type II reference design (see the Chapter 5) should
be designed to manage the processor TDP at an inlet temperature of
35 °C + 0.5 °C = 35.5 °C.
The slope of the thermal profile was established assuming a
generational improvement in thermal solution performance of the
Intel reference design. For an example of Intel Core™2 Duo
processor E8000 series with 6 MB in ATX platform, its improvement
is about 15% over the Intel reference design (E18764-001). This
performance is expressed as the slope on the thermal profile and
can be thought of as the thermal resistance of the heatsink
attached to the processor, ΨCA (Refer to Section 3.1). The
intercept on the thermal profile assumes a maximum ambient
operating condition that is consistent with the available chassis
solutions.
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Processor Thermal/Mechanical Information
18 Thermal and Mechanical Design Guidelines
The thermal profiles for the Intel Core™2 Duo processor E8000
series with 6 MB cache, Intel Core™2 Duo processor E7000 series
with 3 MB cache, and Intel Pentium dual-core processor E6000 and
E5000 series with 2 MB cache, and Intel Celeron processor E3000
series with 1 MB cache are defined such that there is a single
thermal solution for all of the 775_VR_CONFIG_06 processors.
To determine compliance to the thermal profile, a measurement of
the actual processor power dissipation is required. The measured
power is plotted on the Thermal Profile to determine the maximum
case temperature. Using the example in Figure 2-3 for a processor
dissipating 50 W the maximum case temperature is 58 °C. See the
datasheet for the thermal profile.
Figure 2-3. Example Thermal Profile
2.2.4 TCONTROL
TCONTROL defines the maximum operating temperature for the
digital thermal sensor when the thermal solution fan speed is being
controlled by the digital thermal sensor. The TCONTROL parameter
defines a very specific processor operating region where fan speed
can be reduced. This allows the system integrator a method to
reduce the acoustic noise of the processor cooling solution, while
maintaining compliance to the processor thermal specification.
Note: The TCONTROL value for the processor is relative to the
Thermal Control Circuit (TCC) activation set point which will be
seen as 0 using the digital thermal sensor. As a result the
TCONTROL value will always be a negative number. See Chapter 4 for
the discussion the thermal management logic and features and
Chapter 7 on Intel Quiet System Technology (Intel QST).
The value of TCONTROL is driven by a number of factors. One of
the most significant of these is the processor idle power. As a
result a processor with a high (closer to 0) TCONTROL will
dissipate more power than a part with lower value (farther from 0,
such as larger negative number) of TCONTROL when running the same
application.
40
50
60
70
0 10 20 30 40 50 60 70
Power (W)
Cas
e Te
mpe
ratu
re (
°C)
Thermal ProfileTDP
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Processor Thermal/Mechanical Information
Thermal and Mechanical Design Guidelines 19
This is achieved in part by using the ΨCA versus RPM and RPM
versus Acoustics (dBA) performance curves from the Intel enabled
thermal solution. A thermal solution designed to meet the thermal
profile would be expected to provide similar acoustic performance
of different parts with potentially different TCONTROL values.
The value for TCONTROL is calculated by the system BIOS based on
values read from a factory configured processor register. The
result can be used to program a fan speed control component. See
the appropriate processor datasheet for further details on reading
the register and calculating TCONTROL.
See Chapter 7, Intel® Quiet System Technology (Intel® QST), for
details on implementing a design using TCONTROL and the Thermal
Profile.
2.3 Heatsink Design Considerations To remove the heat from the
processor, three basic parameters should be considered:
• The area of the surface on which the heat transfer takes
place. Without any enhancements, this is the surface of the
processor package IHS. One method used to improve thermal
performance is by attaching a heatsink to the IHS. A heatsink can
increase the effective heat transfer surface area by conducting
heat out of the IHS and into the surrounding air through fins
attached to the heatsink base.
• The conduction path from the heat source to the heatsink fins.
Providing a direct conduction path from the heat source to the
heatsink fins and selecting materials with higher thermal
conductivity typically improves heatsink performance. The length,
thickness, and conductivity of the conduction path from the heat
source to the fins directly impact the thermal performance of the
heatsink. In particular, the quality of the contact between the
package IHS and the heatsink base has a higher impact on the
overall thermal solution performance as processor cooling
requirements become stricter. Thermal interface material (TIM) is
used to fill in the gap between the IHS and the bottom surface of
the heatsink, and thereby improve the overall performance of the
stack-up (IHS-TIM-Heatsink). With extremely poor heatsink interface
flatness or roughness, TIM may not adequately fill the gap. The TIM
thermal performance depends on its thermal conductivity as well as
the pressure applied to it. Refer to Section 2.3.4 and Appendix C
for further information on TIM and on bond line management between
the IHS and the heatsink base.
• The heat transfer conditions on the surface on which heat
transfer takes place. Convective heat transfer occurs between the
airflow and the surface exposed to the flow. It is characterized by
the local ambient temperature of the air, TA, and the local air
velocity over the surface. The higher the air velocity over the
surface, and the cooler the air, the more efficient is the
resulting cooling. The nature of the airflow can also enhance heat
transfer using convection. Turbulent flow can provide improvement
over laminar flow. In the case of a heatsink, the surface exposed
to the flow includes in particular the fin faces and the heatsink
base.
Active heatsinks typically incorporate a fan that helps manage
the airflow through the heatsink.
Passive heatsink solutions require in-depth knowledge of the
airflow in the chassis. Typically, passive heatsinks see lower air
speed. These heatsinks are therefore typically larger (and heavier)
than active heatsinks due to the increase in fin surface
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Processor Thermal/Mechanical Information
20 Thermal and Mechanical Design Guidelines
required to meet a required performance. As the heatsink fin
density (the number of fins in a given cross-section) increases,
the resistance to the airflow increases: it is more likely that the
air travels around the heatsink instead of through it, unless air
bypass is carefully managed. Using air-ducting techniques to manage
bypass area can be an effective method for controlling airflow
through the heatsink.
2.3.1 Heatsink Size
The size of the heatsink is dictated by height restrictions for
installation in a system and by the real estate available on the
motherboard and other considerations for component height and
placement in the area potentially impacted by the processor
heatsink. The height of the heatsink must comply with the
requirements and recommendations published for the motherboard form
factor of interest. Designing a heatsink to the recommendations may
preclude using it in system adhering strictly to the form factor
requirements, while still in compliance with the form factor
documentation.
For the ATX/microATX form factor, it is recommended to use:
• The ATX motherboard keep-out footprint definition and height
restrictions for enabling components, defined for the platforms
designed with the LGA775 socket in Appendix G of this design
guide.
• The motherboard primary side height constraints defined in the
ATX Specification V2.1 and the microATX Motherboard Interface
Specification V1.1 found at http://www.formfactors.org/.
The resulting space available above the motherboard is generally
not entirely available for the heatsink. The target height of the
heatsink must take into account airflow considerations (for fan
performance for example) as well as other design considerations
(air duct, and so forth).
For BTX form factor, it is recommended to use:
• The BTX motherboard keep-out footprint definitions and height
restrictions for enabling components for platforms designed with
the LGA77 socket in Appendix G of this design guide.
• An overview of other BTX system considerations for thermal
solutions can be obtained in the latest version of the Balanced
Technology Extended (BTX) System Design Guide found at
http://www.formfactors.org/.
2.3.2 Heatsink Mass
With the need to push air cooling to better performance,
heatsink solutions tend to grow larger (increase in fin surface)
resulting in increased mass. The insertion of highly thermally
conductive materials like copper to increase heatsink thermal
conduction performance results in even heavier solutions. As
mentioned in Section 2.1, the heatsink mass must take into
consideration the package and socket load limits, the heatsink
attach mechanical capabilities, and the mechanical shock and
vibration profile targets. Beyond a certain heatsink mass, the cost
of developing and implementing a heatsink attach mechanism that can
ensure the system integrity under the mechanical shock and
vibration profile targets may become prohibitive.
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Processor Thermal/Mechanical Information
Thermal and Mechanical Design Guidelines 21
The recommended maximum heatsink mass for the ATX thermal
solution is 550g. This mass includes the fan and the heatsink only.
The attach mechanism (clip, fasteners, and so forth) are not
included.
The mass limit for BTX heatsinks that use Intel reference design
structural ingredients is 900 grams. The BTX structural reference
component strategy and design is reviewed in depth in the latest
version of the Balanced Technology Extended (BTX) System Design
Guide.
Note: The 550g mass limit for ATX solutions is based on the
capabilities of the reference design components that retain the
heatsink to the board and apply the necessary preload. Any reuse of
the clip and fastener in derivative designs should not exceed 550g.
ATX Designs that have a mass of greater than 550g should analyze
the preload as discussed in Appendix A and retention limits of the
fastener.
Note: The chipset components on the board are affected by
processor heatsink mass. Exceeding these limits may require the
evaluation of the chipset for shock and vibration.
2.3.3 Package IHS Flatness
The package IHS flatness for the product is specified in the
datasheet and can be used as a baseline to predict heatsink
performance during the design phase.
Intel recommends testing and validating heatsink performance in
full mechanical enabling configuration to capture any impact of IHS
flatness change due to combined socket and heatsink loading. While
socket loading alone may increase the IHS warpage, the heatsink
preload redistributes the load on the package and improves the
resulting IHS flatness in the enabled state.
2.3.4 Thermal Interface Material Thermal interface material
application between the processor IHS and the heatsink base is
generally required to improve thermal conduction from the IHS to
the heatsink. Many thermal interface materials can be pre-applied
to the heatsink base prior to shipment from the heatsink supplier
and allow direct heatsink attach, without the need for a separate
thermal interface material dispense or attach process in the final
assembly factory.
All thermal interface materials should be sized and positioned
on the heatsink base in a way that ensures the entire processor IHS
area is covered. It is important to compensate for
heatsink-to-processor attach positional alignment when selecting
the proper thermal interface material size.
When pre-applied material is used, it is recommended to have a
protective application tape over it. This tape must be removed
prior to heatsink installation.
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Processor Thermal/Mechanical Information
22 Thermal and Mechanical Design Guidelines
2.4 System Thermal Solution Considerations
2.4.1 Chassis Thermal Design Capabilities
The Intel reference thermal solutions and Intel Boxed Processor
thermal solutions assume that the chassis delivers a maximum TA at
the inlet of the processor fan heatsink. The following tables show
the TA requirements for the reference solutions and Intel Boxed
Processor thermal solutions.
Table 2–1. Heatsink Inlet Temperature of Intel® Reference
Thermal Solutions
Topic ATX E18764-0011 BTX Type II
Heatsink Inlet Temperature 40 °C 35.5 °C
NOTE: 1. Intel reference designs (E18764-001) for ATX assume the
use of the thermally
advantaged chassis (refer to Thermally Advantaged Chassis (TAC)
Design Guide for TAC thermal and mechanical requirements). The TAC
2.0 Design Guide defines a new processor cooling solution inlet
temperature target of 40 °C. The existing TAC 1.1 chassis can be
compatible with TAC 2.0 guidelines.
Table 2–2. Heatsink Inlet Temperature of Intel® Boxed Processor
Thermal Solutions
Topic Boxed Processor for Intel® Core™2 Duo Processor E8000,
E7000 Series, Intel® Pentium® Dual-Core
Processor E6000, E5000 Series, and Intel® Celeron® Processor
E3000 Series
Heatsink Inlet Temperature 40 °C
NOTE: 1. Boxed Processor thermal solutions for ATX assume the
use of the thermally advantaged
chassis (refer to Thermally Advantaged Chassis (TAC) Design
Guide for TAC thermal and mechanical requirements). The TAC 2.0
Design Guide defines a new processor cooling solution inlet
temperature target of 40 °C. The existing TAC 1.1 chassis can be
compatible with TAC 2.0 guidelines.
2.4.2 Improving Chassis Thermal Performance The heat generated
by components within the chassis must be removed to provide an
adequate operating environment for both the processor and other
system components. Moving air through the chassis brings in air
from the external ambient environment and transports the heat
generated by the processor and other system components out of the
system. The number, size and relative position of fans and vents
determine the chassis thermal performance, and the resulting
ambient temperature around the processor. The size and type
(passive or active) of the thermal solution and the amount of
system airflow can be traded off against each other to meet
specific system design constraints. Additional constraints are
board layout, spacing, component placement, acoustic requirements,
and structural considerations that limit the thermal solution size.
For more information, refer to the Performance ATX Desktop System
Thermal Design Suggestions or Performance microATX Desktop System
Thermal Design Suggestions or Balanced Technology Extended (BTX)
System Design Guide documents available on the
http://www.formfactors.org/ web site.
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Processor Thermal/Mechanical Information
Thermal and Mechanical Design Guidelines 23
In addition to passive heatsinks, fan heatsinks and system fans
are other solutions that exist for cooling integrated circuit
devices. For example, ducted blowers, heat pipes, and liquid
cooling are all capable of dissipating additional heat. Due to
their varying attributes, each of these solutions may be
appropriate for a particular system implementation.
To develop a reliable, cost-effective thermal solution, thermal
characterization and simulation should be carried out at the entire
system level, accounting for the thermal requirements of each
component. In addition, acoustic noise constraints may limit the
size, number, placement, and types of fans that can be used in a
particular design.
To ease the burden on thermal solutions, the Thermal Monitor
feature and associated logic have been integrated into the silicon
of the processor. By taking advantage of the Thermal Monitor
feature, system designers may reduce thermal solution cost by
designing to TDP instead of maximum power. Thermal Monitor attempts
to protect the processor during sustained workload above TDP.
Implementation options and recommendations are described in Chapter
4.
2.4.3 Summary In summary, considerations in heatsink design
include:
• The local ambient temperature TA at the heatsink, which is a
function of chassis design.
• The thermal design power (TDP) of the processor, and the
corresponding maximum TC as calculated from the thermal profile.
These parameters are usually combined in a single lump cooling
performance parameter, ΨCA (case to air thermal characterization
parameter). More information on the definition and the use of ΨCA
is given Section 3.1.
• Heatsink interface to IHS surface characteristics, including
flatness and roughness.
• The performance of the thermal interface material used between
the heatsink and the IHS.
• The required heatsink clip static load, between 18 lbf to 70
lbf throughout the life of the product (Refer to Section 2.1.2.2
for further information).
• Surface area of the heatsink. • Heatsink material and
technology.
• Volume of airflow over the heatsink surface area. •
Development of airflow entering and within the heatsink area.
• Physical volumetric constraints placed by the system
2.5 System Integration Considerations Manufacturing with Intel®
Components using 775–Land LGA Package and LGA775 Socket
documentation provides Best Known Methods for all aspects LGA775
socket based platforms and systems manufacturing. Of particular
interest for package and heatsink installation and removal is the
System Assembly module. A video covering system integration is also
available. Contact your Intel field sales representative for
further information.
§
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Processor Thermal/Mechanical Information
24 Thermal and Mechanical Design Guidelines
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Thermal Metrology
Thermal and Mechanical Design Guidelines 25
3 Thermal Metrology This section discusses guidelines for
testing thermal solutions, including measuring processor
temperatures. In all cases, the thermal engineer must measure power
dissipation and temperature to validate a thermal solution. To
define the performance of a thermal solution the “thermal
characterization parameter”, Ψ (“psi”) will be used.
3.1 Characterizing Cooling Performance Requirements
The idea of a “thermal characterization parameter”, Ψ (“psi”),
is a convenient way to characterize the performance needed for the
thermal solution and to compare thermal solutions in identical
situations (same heat source and local ambient conditions). The
thermal characterization parameter is calculated using total
package power.
Note: Heat transfer is a three-dimensional phenomenon that can
rarely be accurately and easily modeled by a single resistance
parameter like Ψ.
The case-to-local ambient thermal characterization parameter
value (ΨCA) is used as a measure of the thermal performance of the
overall thermal solution that is attached to the processor package.
It is defined by the following equation, and measured in units of
°C/W:
ΨCA = (TC – TA) / PD (Equation 1)
Where:
ΨCA = Case-to-local ambient thermal characterization parameter
(°C/W) TC = Processor case temperature (°C) TA = Local ambient
temperature in chassis at processor (°C) PD = Processor total power
dissipation (W) (assumes all power dissipates
through the IHS)
The case-to-local ambient thermal characterization parameter of
the processor, ΨCA, is comprised of ΨCS, the thermal interface
material thermal characterization parameter, and of ΨSA, the
sink-to-local ambient thermal characterization parameter:
ΨCA = ΨCS + ΨSA (Equation 2)
Where:
ΨCS = Thermal characterization parameter of the thermal
interface material (°C/W)
ΨSA = Thermal characterization parameter from heatsink-to-local
ambient (°C/W)
ΨCS is strongly dependent on the thermal conductivity and
thickness of the TIM between the heatsink and IHS.
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Thermal Metrology
26 Thermal and Mechanical Design Guidelines
ΨSA is a measure of the thermal characterization parameter from
the bottom of the heatsink to the local ambient air. ΨSA is
dependent on the heatsink material, thermal conductivity, and
geometry. It is also strongly dependent on the air velocity through
the fins of the heatsink.
Figure 3-1 illustrates the combination of the different thermal
characterization parameters.
Figure 3-1. Processor Thermal Characterization Parameter
Relationships
TIMTS
TA
ΨCA
LGA775 Socket
ProcessorIHS
System Board
TC
Heatsink
TIMTS
TA
ΨCA
LGA775 Socket
ProcessorIHS
System Board
TC
Heatsink
3.1.1 Example
The cooling performance, ΨCA, is defined using the principle of
thermal characterization parameter described above:
• The case temperature TC-MAX and thermal design power TDP given
in the processor datasheet.
• Define a target local ambient temperature at the processor,
TA.
Since the processor thermal profile applies to all processor
frequencies, it is important to identify the worst case (lowest
ΨCA) for a targeted chassis characterized by TA to establish a
design strategy.
The following provides an illustration of how one might
determine the appropriate performance targets. The example power
and temperature numbers used here are not related to any specific
Intel processor thermal specifications, and are for illustrative
purposes only.
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Thermal Metrology
Thermal and Mechanical Design Guidelines 27
Assume the TDP, as listed in the datasheet, is 100 W and the
maximum case temperature from the thermal profile for 100 W is 67
°C. Assume as well that the system airflow has been designed such
that the local ambient temperature is 38 °C. Then, the following
could be calculated using equation 1 from above:
ΨCA = (TC, − TA) / TDP = (67 – 38) / 100 = 0.29 °C/W
To determine the required heatsink performance, a heatsink
solution provider would need to determine ΨCS performance for the
selected TIM and mechanical load configuration. If the heatsink
solution were designed to work with a TIM material performing at
ΨCS ≤ 0.10 °C/W, solving for equation 2 from above, the performance
of the heatsink would be:
ΨSA = ΨCA − ΨCS = 0.29 − 0.10 = 0.19 °C/W
3.2 Processor Thermal Solution Performance Assessment
Thermal performance of a heatsink should be assessed using a
thermal test vehicle (TTV) provided by Intel. The TTV is a stable
heat source that the user can make accurate power measurement,
whereas processors can introduce additional factors that can impact
test results. In particular, the power level from actual processors
varies significantly, even when running the maximum power
application provided by Intel, due to variances in the
manufacturing process. The TTV provides consistent power and power
density for thermal solution characterization and results can be
easily translated to real processor performance. Accurate
measurement of the power dissipated by an actual processor is
beyond the scope of this document.
Once the thermal solution is designed and validated with the
TTV, it is strongly recommended to verify functionality of the
thermal solution on real processors and on fully integrated
systems. The Intel maximum power application enables steady power
dissipation on a processor to assist in this testing. This maximum
power application is provided by Intel.
3.3 Local Ambient Temperature Measurement Guidelines
The local ambient temperature TA is the temperature of the
ambient air surrounding the processor. For a passive heatsink, TA
is defined as the heatsink approach air temperature; for an
actively cooled heatsink, it is the temperature of inlet air to the
active cooling fan.
It is worthwhile to determine the local ambient temperature in
the chassis around the processor to understand the effect it may
have on the case temperature.
TA is best measured by averaging temperature measurements at
multiple locations in the heatsink inlet airflow. This method helps
reduce error and eliminate minor spatial variations in temperature.
The following guidelines are meant to enable accurate determination
of the localized air temperature around the processor during system
thermal testing.
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Thermal Metrology
28 Thermal and Mechanical Design Guidelines
For active heatsinks, it is important to avoid taking
measurement in the dead flow zone that usually develops above the
fan hub and hub spokes. Measurements should be taken at four
different locations uniformly placed at the center of the annulus
formed by the fan hub and the fan housing to evaluate the
uniformity of the air temperature at the fan inlet. The
thermocouples should be placed approximately 3 mm to 8 mm [0.1 to
0.3 in] above the fan hub vertically and halfway between the fan
hub and the fan housing horizontally as shown in the ATX heatsink
in Figure 3-2 (avoiding the hub spokes). Using an open bench to
characterize an active heatsink can be useful, and usually ensures
more uniform temperatures at the fan inlet. However, additional
tests that include a solid barrier above the test motherboard
surface can help evaluate the potential impact of the chassis. This
barrier is typically clear Plexiglas*, extending at least 100 mm [4
in] in all directions beyond the edge of the thermal solution.
Typical distance from the motherboard to the barrier is 81 mm [3.2
in]. For even more realistic airflow, the motherboard should be
populated with significant elements like memory cards, graphic
card, and chipset heatsink. If a barrier is used, the thermocouple
can be taped directly to the barrier with a clear tape at the
horizontal location as previously described, half way between the
fan hub and the fan housing. If a variable speed fan is used, it
may be useful to add a thermocouple taped to the barrier above the
location of the temperature sensor used by the fan to check its
speed setting against air temperature. When measuring TA in a
chassis with a live motherboard, add-in cards, and other system
components, it is likely that the TA measurements will reveal a
highly non-uniform temperature distribution across the inlet fan
section.
For passive heatsinks, thermocouples should be placed
approximately 13 mm to 25 mm [0.5 to 1.0 in] away from processor
and heatsink as shown in Figure 3-3. The thermocouples should be
placed approximately 51 mm [2.0 in] above the baseboard. This
placement guideline is meant to minimize the effect of localized
hot spots from baseboard components.
Note: Testing an active heatsink with a variable speed fan can
be done in a thermal chamber to capture the worst-case thermal
environment scenarios. Otherwise, when doing a bench top test at
room temperature, the fan regulation prevents the heatsink from
operating at its maximum capability. To characterize the heatsink
capability in the worst-case environment in these conditions, it is
then necessary to disable the fan regulation and power the fan
directly, based on guidance from the fan supplier.
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Thermal Metrology
Thermal and Mechanical Design Guidelines 29
Figure 3-2. Locations for Measuring Local Ambient Temperature,
Active ATX Heatsink
Note: Drawing Not to Scale
Figure 3-3. Locations for Measuring Local Ambient Temperature,
Passive Heatsink
Note: Drawing Not to Scale
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Thermal Metrology
30 Thermal and Mechanical Design Guidelines
3.4 Processor Case Temperature Measurement Guidelines
To ensure functionality and reliability, the processor is
specified for proper operation when TC is maintained at or below
the thermal profile as listed in the datasheet. The measurement
location for TC is the geometric center of the IHS. Figure 2-2
shows the location for TC measurement.
Special care is required when measuring TC to ensure an accurate
temperature measurement. Thermocouples are often used to measure
TC. Before any temperature measurements are made, the thermocouples
must be calibrated, and the complete measurement system must be
routinely checked against known standards. When measuring the
temperature of a surface that is at a different temperature from
the surrounding local ambient air, errors could be introduced in
the measurements. The measurement errors could be caused by poor
thermal contact between the junction of the thermocouple and the
surface of the integrated heat spreader, heat loss by radiation,
convection, by conduction through thermocouple leads, or by contact
between the thermocouple cement and the heatsink base.
Appendix D defines a reference procedure for attaching a
thermocouple to the IHS of a 775-Land LGA processor package for TC
measurement. This procedure takes into account the specific
features of the 775-Land LGA package and of the LGA775 socket for
which it is intended.
§
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Thermal Management Logic and Thermal Monitor Feature
Thermal and Mechanical Design Guidelines 31
4 Thermal Management Logic and Thermal Monitor Feature
4.1 Processor Power Dissipation An increase in processor
operating frequency not only increases system performance, but also
increases the processor power dissipation. The relationship between
frequency and power is generalized in the following equation:
P = CV2F (where P = power, C = capacitance, V = voltage, F =
frequency)
From this equation, it is evident that power increases linearly
with frequency and with the square of voltage. In the absence of
power saving technologies, ever increasing frequencies will result
in processors with power dissipations in the hundreds of watts.
Fortunately, there are numerous ways to reduce the power
consumption of a processor, and Intel is aggressively pursuing low
power design techniques. For example, decreasing the operating
voltage, reducing unnecessary transistor activity, and using more
power efficient circuits can significantly reduce processor power
consumption.
An on-die thermal management feature called Thermal Monitor is
available on the processor. It provides a thermal management
approach to support the continued increases in processor frequency
and performance. By using a highly accurate on-die temperature
sensing circuit and a fast acting Thermal Control Circuit (TCC),
the processor can rapidly initiate thermal management control. The
Thermal Monitor can reduce cooling solution cost, by allowing
thermal designs to target TDP.
The processor also supports an additional power reduction
capability known as Thermal Monitor 2 described in Section
4.2.3.
4.2 Thermal Monitor Implementation The Thermal Monitor consists
of the following components:
• A highly accurate on-die temperature sensing circuit
• A bi-directional signal (PROCHOT#) that indicates if the
processor has exceeded its maximum temperature or can be asserted
externally to activate the Thermal Control Circuit (TCC) (see
Section 4.2.1 for more details on user activation of TCC using the
PROCHOT# signal)
• A Thermal Control Circuit that will attempt to reduce
processor temperature by rapidly reducing power consumption when
the on-die temperature sensor indicates that it has exceeded the
maximum operating point.
• Registers to determine the processor thermal status.
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Thermal Management Logic and Thermal Monitor Feature
32 Thermal and Mechanical Design Guidelines
4.2.1 PROCHOT# Signal
The primary function of the PROCHOT# signal is to provide an
external indication that the processor has reached the TCC
activation temperature. While PROCHOT# is asserted, the TCC will be
activated. Assertion of the PROCHOT# signal is independent of any
register settings within the processor. It is asserted any time the
processor die temperature reaches the trip point.
PROCHOT# can be configured using BIOS as an output or
bi-directional signal. As an output, PROCHOT# will go active when
the processor temperature of either core reaches the TCC activation
temperature. As an input, assertion of PROCHOT# will activate the
TCC for both cores. The TCC will remain active until the system
de-asserts PROCHOT#
The temperature at which the PROCHOT# signal goes active is
individually calibrated during manufacturing. Once configured, the
processor temperature at which the PROCHOT# signal is asserted is
not re-configurable.
One application of the Bi-directional PROCHOT# is for the
thermal protection of voltage regulators (VR). System designers can
implement a circuit to monitor the VR temperature and activate the
TCC when the temperature limit of the VR is reached. By asserting
PROCHOT# (pulled-low) which activates the TCC, the VR can cool down
as a result of reduced processor power consumption. Bi-directional
PROCHOT# can allow VR thermal designs to target maximum sustained
current instead of maximum current. Systems should still provide
proper cooling for the VR, and rely on bi-directional PROCHOT#
signal only as a backup in case of system cooling failure.
Note: A thermal solution designed to meet the thermal profile
specifications should rarely experience activation of the TCC as
indicated by the PROCHOT# signal going active.
4.2.2 Thermal Control Circuit
The Thermal Control Circuit portion of the Thermal Monitor must
be enabled for the processor to operate within specifications. The
Thermal Monitor’s TCC, when active, will attempt to lower the
processor temperature by reducing the processor power consumption.
There are two methods by which TCC can reduce processor power
dissipation. These methods are referred to as Thermal Monitor 1
(TM1) and Thermal Monitor 2 (TM2).
4.2.2.1 Thermal Monitor
In the original implementation of thermal monitor this is done
by changing the duty cycle of the internal processor clocks,
resulting in a lower effective frequency. When active, the TCC
turns the processor clocks off and then back on with a
predetermined duty cycle. The duty cycle is processor specific, and
is fixed for a particular processor. The maximum time period the
clocks are disabled is ~3 µs. This time period is frequency
dependent and higher frequency processors will disable the internal
clocks for a shorter time period. Figure 4-1 illustrates the
relationship between the internal processor clocks and
PROCHOT#.
Performance counter registers, status bits in model specific
registers (MSRs), and the PROCHOT# output pin are available to
monitor the Thermal Monitor behavior.
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Thermal Management Logic and Thermal Monitor Feature
Thermal and Mechanical Design Guidelines 33
Figure 4-1. Thermal Monitor Control
PROCHOT#
Resultant internal clock
Normal clock
Internal clock Duty cycle control
4.2.3 Thermal Monitor 2
The second method of power reduction is TM2. TM2 provides an
efficient means of reducing the power consumption within the
processor and limiting the processor temperature.
When TM2 is enabled, and a high temperature situation is
detected, the enhanced TCC will be activated. The enhanced TCC
causes the processor to adjust its operating frequency (by dropping
the bus-to-core multiplier to its minimum available value) and
input voltage identification (VID) value. This combination of
reduced frequency and VID results in a reduction in processor power
consumption.
A processor enabled for TM2 includes two operating points, each
consisting of a specific operating frequency and voltage. The first
operating point represents the normal operating condition for the
processor.
The second operating point consists of both a lower operating
frequency and voltage. When the TCC is activated, the processor
automatically transitions to the new frequency. This transition
occurs very rapidly (on the order of 5 microseconds). During the
frequency transition, the processor is unable to service any bus
requests, all bus traffic is blocked. Edge-triggered interrupts
will be latched and kept pending until the processor resumes
operation at the new frequency.
Once the new operating frequency is engaged, the processor will
transition to the new core operating voltage by issuing a new VID
code to the voltage regulator. The voltage regulator must support
VID transitions in order to support TM2. During the voltage change,
it will be necessary to transition through multiple VID codes to
reach the target operating voltage. Each step will be one VID table
entry (that is, 12.5 mV steps). The processor continues to execute
instructions during the voltage transition. Operation at the lower
voltage reduces the power consum